Today, Google is marking the 40th anniversary of the Rubik’s Cube with an interactive Google Doodle in which you can manipulate a virtual cube. See a video demonstration here. It’s as good a day as any to celebrate the toy, although the exact date of its invention is not recorded anywhere I can find. Erno Rubik developed the gadget in the spring of 1974 to model spatial relationships to his students. He was more concerned with the internal mechanism, and did not realize he had invented a puzzle until he tried to restore it to its original configuration himself. The toy was first marketed in 1977 in Hungary, and worldwide in 1980.